Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932465Ab3ICDyY (ORCPT ); Mon, 2 Sep 2013 23:54:24 -0400 Received: from mga01.intel.com ([192.55.52.88]:23290 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932365Ab3ICDxD (ORCPT ); Mon, 2 Sep 2013 23:53:03 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.89,1011,1367996400"; d="scan'208";a="395808044" From: Tom Zanussi To: rostedt@goodmis.org Cc: masami.hiramatsu.pt@hitachi.com, linux-kernel@vger.kernel.org, Tom Zanussi Subject: [PATCH v8 00/10] tracing: trace event triggers Date: Mon, 2 Sep 2013 22:52:16 -0500 Message-Id: X-Mailer: git-send-email 1.7.11.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 30075 Lines: 623 Hi, This is v8 of the trace event triggers patchset. This version addresses the comments and feedback from Steve Rostedt on v7. v8: - changed rcu_dereference_raw() to rcu_dereference() and moved synchronize_sched() out from under the syscall_trace_lock mutex. - got rid of the various void ** usages in the basic framework and individual trigger patches. Since triggers always expect an event_trigger_data instance, there's not even any reason to make it a void *, so those along with the void * usages were changed to use event_trigger_data * directly. To allow for trigger-specific data, a new void * field named private_data was added to event_trigger_data; this is made use of by the enable/disable_event triggers. - fixed various style nitpicks. - added a new TRIGGER_COND flag to ftrace_file - this flag basically tracks whether or not an event has any triggers that have a condition associated with them that requires looking at the data being logged (or that would be in the case of soft-disable) for the current event. If TRIGGER_COND is not set, then the triggers can be invoked immediately without forcing the ineffeciency of actually generating the log event when not necessary. - patch 8 removed the obsolete filter_current_check_discard() and replaced it with filter_check_discard() but accidentally made the new function static inline, which is obviously not what was intended. That and the new call_filter_check_discard() functions are now normal functions as filter_current_check_discard() was. - isolated all the ugly 'if (USE_CALL_FILTER) else' usages in patch 8 which significantly cleaned up that patch as a result. v7: - moved find_event_file() extern declartion to patch 06. - moved helper functions from patch 02 to 03, where they're first used. - removed copies of cmd_ops fields from trigger_data and changed to use cmd_ops diretly instead. - renamed trigger_mode to trigger_type to avoid confusion with the FTRACE_EVENT_FL_TRIGGER_MODE_BIT bitflag, and fixed up usage/documentation, etc. v6: - fixed up the conflicts in trace_events.c related to the actual creation of the per-event 'trigger' files. v5: - got rid of the trigger_iterator, a vestige of the first patchset, which attempted to abstract the ftrace_iterator for triggers, and cleaned up related code simplified as a result. - replaced the void *cmd_data everywhere with ftrace_event_file *, another vestige of the initial patchset. - updated the patchset to use event_file_data() to grab the i_private ftrace_event_files where appropriate (this was a separate patch in the previous patchset, but was merged into the basic framework patch as suggested by Masami. The only interesting part about this is that it moved event_file_data() from kernel/trace/trace_events.c to kernel/trace/trace.h so it can be used in e.g. trace_events_trigger.c as well.) - add missing grab of event_mutex in event_trigger_regex_write(). - realized when making the above changes that the trigger filters weren't being freed when the trigger was freed, so added a trigger_data_free() to do that. It also ensures that trigger_data won't be freed until nothing is using it. - added clear_event_triggers(), which clears all triggers in a trace array (and soft-disable associated with event_enable/disable events). - added a comment to ftrace_syscall_enter/exit to document the use of rcu_dereference_raw() there. v4: - made some changes to the soft-disable for syscall patch, according to Masami's suggestions. Actually, since there's now an array of ftrace_files for syscalls that can serve the same purpose, the enabled_enter/exit_syscalls bit arrays became redundant and were removed. - moved all the remaining common functions out of the traceon/traceoff patch and into the basic trigger framework patch and added comments to all the common functions. - extensively commented the event_trigger_ops and event_command ops. - made the register/unregister_command functions __init. Since that code was originally inspired by similar ftrace code, a new patch was added to do the same thing for the register/unregister of the ftrace commands (patch 10/11). - fixed the event_trigger_regex_open i_private problem noted by Masami that's currently being addressed by Oleg Nesterov's fixes for this. Note that that patchset also affects patch 8/11 (update filters for multi-buffer, since it touches event filters as well). Patch 11/11 depends on that patchset and also moves event_file_data() to trace.h.b v3: - added a new patch to the series (patch 8/9 - update event filters for multibuffer) to bring the event filters up-to-date wrt the multibuffer changes - without this patch, the same filter is applied to all buffers regardless of which instance sets it; this patch allows you to set per-instance filters as you'd expect. The one exception to this is the 'ftrace subsystem' events, which are special and retain their current behavior. - changed the syscall soft enabling to keep a per-trace-array array of trace_event_files alongside the 'enabled' bitmaps there. This keeps them in a place where they're only allocated for tracing and which I think addresses all the previous comments for that patch. v2: - removed all changes to __ftrace_event_enable_disable() (except for patch 04/11 which clears the soft_disabled bit as discussed) and created a separate trace_event_trigger_enable_disable() that calls it after setting/clearing the TRIGGER_MODE_BIT. - added a trigger_mode enum for future patches that break up the trigger calls for filtering, but that's also now used as a command id for registering/unregistering commands. - removed the enter_file/exit_file members that were added to syscall_metadata after realizing that they were unnecessary if ftrace_syscall_enter/exit() were modified to receive a pointer to the ftrace_file instead of the pointer to the trace_array in the ftrace_file. - broke up the trigger invocation into two parts so that triggers like 'stacktrace' that themselves log into the trace buffer can defer the actual trigger invocation until after the current record is closed, which is needed for the filter check that in turn determines whether the trigger gets invoked. - other minor cleanup This patchset implements 'trace event triggers', which are similar to the function triggers implemented for 'ftrace filter commands' (see 'Filter commands' in Documentation/trace/ftrace.txt), but instead of being invoked from function calls are invoked by trace events. Basically the patchset allows 'commands' to be triggered whenever a given trace event is hit. The set of commands implemented by this patchset are: - enable/disable_event - enable or disable another event whenever the trigger event is hit - stacktrace - dump a stacktrace to the trace buffer whenever the trigger event is hit - snapshot - create a snapshot of the current trace buffer whenever the trigger event is hit - traceon/traceoff - turn tracing on or off whenever the trigger event is hit Triggers can also be conditionally invoked by associating a standard trace event filter with them - if the given event passes the filter, the trigger is invoked, otherwise it's not. (see 'Event filtering' in Documentation/trace/events.txt for info on event filters). See the last patch in the series for more complete documention on event triggers and the available trigger commands, and below for some simple examples of each of the above commands along with conditional filtering. The first four patches are bugfix patches or minor improvements which can be applied regardless; the rest contain the basic framework and implementations for each command. This patchset was based on some ideas from Steve Rostedt, which he outlined during a couple discussions at ELC and follow-on e-mails. Code- and interface-wise, it's also partially based on the existing function triggers implementation and essentially works on top of the SOFT_DISABLE mode introduced for that. Both Steve and Masami Hiramatsu took a look at a couple early versions of this patchset, and offered some very useful suggestions reflected in this patchset - thanks to them both for the ideas and for taking the time to do some basic sanity reviews! Below are a few concrete examples demonstrating each of the available commands. The first example attempts to capture all the kmalloc events that happen as a result of reading a particular file. The first part of the set of commands below adds a kmalloc 'enable_event' trigger to the sys_enter_read trace event - as a result, when the sys_enter_read event occurs, kmalloc events are enabled, resulting in those kmalloc events getting logged into the trace buffer. The :1 at the end of the kmalloc enable_event specifies that the enabling of kmalloc events on sys_enter_read will only happen once - subsequent reads won't trigger the kmalloc logging. The next part of the example reads a test file, which triggers the sys_enter_read tracepoint and thus turns on the kmalloc events, and once done, adds a trigger to sys_exit_read that disables kmalloc events. The disable_event doesn't have a :1 appended, which means it happens on every sys_exit_read. # echo 'enable_event:kmem:kmalloc:1' > \ /sys/kernel/debug/tracing/events/syscalls/sys_enter_read/trigger; \ cat ~/junk.txt > /dev/null; \ echo 'disable_event:kmem:kmalloc' > \ /sys/kernel/debug/tracing/events/syscalls/sys_exit_read/trigger Just to show a bit of what happens under the covers, if we display the kmalloc 'enable' file, we see that it's 'soft disabled' (the asterisk after the enable flag). This means that it's actually enabled but is in the SOFT_DISABLED state, and is essentially held back from actually logging anything to the trace buffer, but can be made to log into the buffer by simply flipping a bit : # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/enable 0* If we look at the 'enable' file for the triggering sys_enter_read trace event, we can see that it also has the 'soft disable' flag set. This is because in the case of the triggering event, we also need to have the trace event invoked regardless of whether or not its actually being logged, so we can process the triggers. This functionality is also built on top of the SOFT_DISABLE flag and is reflected in the enable state as well: # cat /sys/kernel/debug/tracing/events/syscalls/sys_enter_read/enable 0* To find out which triggers are set for a particular event, we can look at the 'trigger' file for the event. Here's what the 'trigger' file for the sys_enter_read event looks like: # cat /sys/kernel/debug/tracing/events/syscalls/sys_enter_read/trigger enable_event:kmem:kmalloc:count=0 The 'count=0' field at the end shows that this trigger has no more triggering ability left - it's essentially fired all its shots - if it was still active, it would have a non-zero count. Looking at the sys_exit_read, we see that since we didn't specify a number at the end, the number of times it can fire is unlimited: # cat /sys/kernel/debug/tracing/events/syscalls/sys_exit_read/trigger disable_event:kmem:kmalloc:unlimited # cat /sys/kernel/debug/tracing/events/syscalls/sys_exit_read/enable 0* Finally, let's look at the results of the above set of commands by cat'ing the 'trace' file: # cat /sys/kernel/debug/tracing/trace # tracer: nop # # entries-in-buffer/entries-written: 85/85 #P:4 # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / delay # TASK-PID CPU# |||| TIMESTAMP FUNCTION # | | | |||| | | cat-2596 [001] .... 374.518849: kmalloc: call_site=ffffffff812de707 ptr=ffff8800306b9290 bytes_req=2 bytes_alloc=8 gfp_flags=GFP_KERNEL|GFP_ZERO cat-2596 [001] .... 374.518956: kmalloc: call_site=ffffffff81182a12 ptr=ffff88010c8e1500 bytes_req=256 bytes_alloc=256 gfp_flags=GFP_KERNEL|GFP_ZERO cat-2596 [001] .... 374.518959: kmalloc: call_site=ffffffff812d8e49 ptr=ffff88003002a200 bytes_req=32 bytes_alloc=32 gfp_flags=GFP_KERNEL|GFP_ZERO cat-2596 [001] .... 374.518960: kmalloc: call_site=ffffffff812de707 ptr=ffff8800306b9088 bytes_req=2 bytes_alloc=8 gfp_flags=GFP_KERNEL|GFP_ZERO cat-2596 [003] .... 374.519063: kmalloc: call_site=ffffffff812d9f50 ptr=ffff8800b793fd00 bytes_req=256 bytes_alloc=256 gfp_flags=GFP_KERNEL cat-2596 [003] .... 374.519119: kmalloc: call_site=ffffffff811cc3bc ptr=ffff8800b7918900 bytes_req=128 bytes_alloc=128 gfp_flags=GFP_KERNEL cat-2596 [003] .... 374.519122: kmalloc: call_site=ffffffff811cc4d2 ptr=ffff880030404800 bytes_req=504 bytes_alloc=512 gfp_flags=GFP_KERNEL cat-2596 [003] .... 374.519125: kmalloc: call_site=ffffffff811cc64e ptr=ffff88003039d8a0 bytes_req=28 bytes_alloc=32 gfp_flags=GFP_KERNEL . . . Xorg-1194 [000] .... 374.543956: kmalloc: call_site=ffffffffa03a8599 ptr=ffff8800ba23b700 bytes_req=112 bytes_alloc=128 gfp_flags=GFP_TEMPORARY|GFP_NOWARN|GFP_NORETRY Xorg-1194 [000] .... 374.543961: kmalloc: call_site=ffffffffa03a7639 ptr=ffff8800b7905b40 bytes_req=56 bytes_alloc=64 gfp_flags=GFP_TEMPORARY|GFP_ZERO Xorg-1194 [000] .... 374.543973: kmalloc: call_site=ffffffffa039f716 ptr=ffff8800b7905ac0 bytes_req=64 bytes_alloc=64 gfp_flags=GFP_KERNEL . . . compiz-1769 [002] .... 374.547586: kmalloc: call_site=ffffffffa03a8599 ptr=ffff8800ba320400 bytes_req=952 bytes_alloc=1024 gfp_flags=GFP_TEMPORARY|GFP_NOWARN|GFP_NORETRY compiz-1769 [002] .... 374.547592: kmalloc: call_site=ffffffffa03a7639 ptr=ffff8800bd5f7400 bytes_req=280 bytes_alloc=512 gfp_flags=GFP_TEMPORARY|GFP_ZERO compiz-1769 [002] .... 374.547623: kmalloc: call_site=ffffffffa039f716 ptr=ffff8800b792d580 bytes_req=64 bytes_alloc=64 gfp_flags=GFP_KERNEL . . . cat-2596 [000] .... 374.646019: kmalloc: call_site=ffffffff8123df9f ptr=ffff8800ba2f2900 bytes_req=96 bytes_alloc=96 gfp_flags=GFP_NOFS|GFP_ZERO cat-2596 [000] .... 374.648263: kmalloc: call_site=ffffffff8123df9f ptr=ffff8800ba2f2900 bytes_req=96 bytes_alloc=96 gfp_flags=GFP_NOFS|GFP_ZERO cat-2596 [000] .... 374.650503: kmalloc: call_site=ffffffff8123df9f ptr=ffff8800ba2f2900 bytes_req=96 bytes_alloc=96 gfp_flags=GFP_NOFS|GFP_ZERO . . . bash-2425 [002] .... 374.654923: kmalloc: call_site=ffffffff8123df9f ptr=ffff8800b7a28780 bytes_req=96 bytes_alloc=96 gfp_flags=GFP_NOFS|GFP_ZERO rsyslogd-974 [002] .... 374.655163: kmalloc: call_site=ffffffff81046ae6 ptr=ffff8800ba320400 bytes_req=1024 bytes_alloc=1024 gfp_flags=GFP_KERNEL As you can see, we captured all the kmallocs from our 'cat' reads, but also any other kmallocs that happened for other processes between the time we turned on kmalloc events and turned them off. Future work should add a way to screen out unwanted events e.g. the abilitiy to capture the triggering pid in a simple variable and use that variable in event filters to screen out other pids. To turn off the events we turned on, simply reinvoke the commands prefixed by '!': # echo '!enable_event:kmem:kmalloc:1' > /sys/kernel/debug/tracing/events/syscalls/sys_enter_read/trigger # echo '!disable_event:kmem:kmalloc' > /sys/kernel/debug/tracing/events/syscalls/sys_exit_read/trigger You can verify that the events have been turned off by again examining the 'enable' and 'trigger' files: # cat /sys/kernel/debug/tracing/events/syscalls/sys_enter_read/trigger # cat /sys/kernel/debug/tracing/events/syscalls/sys_enter_read/enable 0 # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/enable 0 The next example shows how to use the 'stacktrace' command. To have a stacktrace logged every time a particular event occurs, simply echo 'stacktrace' into the 'trigger' file for that event: # echo 'stacktrace' > /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger stacktrace:unlimited Looking at the 'trace' output, we indeed see stack traces for every kmalloc: # cat /sys/kernel/debug/tracing/trace compiz-1769 [003] .... 2422.614630: => i915_add_request => i915_gem_do_execbuffer.isra.15 => i915_gem_execbuffer2 => drm_ioctl => do_vfs_ioctl => SyS_ioctl => system_call_fastpath Xorg-1194 [002] .... 2422.619076: => drm_wait_vblank => drm_ioctl => do_vfs_ioctl => SyS_ioctl => system_call_fastpath Xorg-1194 [000] .... 2422.625823: => i915_gem_execbuffer2 => drm_ioctl => do_vfs_ioctl => SyS_ioctl => system_call_fastpath . . . bash-2842 [001] .... 2423.002059: => __tracing_open => tracing_open => do_dentry_open => finish_open => do_last => path_openat => do_filp_open => do_sys_open => SyS_open => system_call_fastpath bash-2842 [001] .... 2423.002070: => __tracing_open => tracing_open => do_dentry_open => finish_open => do_last => path_openat => do_filp_open => do_sys_open => SyS_open => system_call_fastpath For an event like kmalloc, however, we don't typically want to see a stack trace for every single event, since the amount of data produced is overwhelming. What we'd typically want to do is only log a stack trace for particular events of interest. We can accomplish that by appending an 'event filter' to the trigger. The event filters used to filter triggers are exactly the same as those implemented for the existing trace event 'filter' files - see the trace event documentation for details. First, let's turn off the existing stacktrace event, and clear the trace buffer: # echo '!stacktrace' > /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger # echo > /sys/kernel/debug/tracing/trace Now, we can add a new stacktrace trigger which will fire 5 times, but only if the number of bytes requested by the caller was greater than or equal to 512: # echo 'stacktrace:5 if bytes_req >= 512' > \ /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger stacktrace:count=0 if bytes_req >= 512 >From looking at the trigger, we can see the event fired 5 times (count=0) and looking at the 'trace' file, we can verify that: # cat trace # tracer: nop # # entries-in-buffer/entries-written: 5/5 #P:4 # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / delay # TASK-PID CPU# |||| TIMESTAMP FUNCTION # | | | |||| | | rsyslogd-974 [000] .... 1796.412997: => kmem_cache_alloc_trace => do_syslog => kmsg_read => proc_reg_read => vfs_read => SyS_read => system_call_fastpath compiz-1769 [000] .... 1796.427342: => __kmalloc => i915_gem_execbuffer2 => drm_ioctl => do_vfs_ioctl => SyS_ioctl => system_call_fastpath Xorg-1194 [003] .... 1796.441251: => __kmalloc => i915_gem_execbuffer2 => drm_ioctl => do_vfs_ioctl => SyS_ioctl => system_call_fastpath Xorg-1194 [003] .... 1796.441392: => __kmalloc => sg_kmalloc => __sg_alloc_table => sg_alloc_table => i915_gem_object_get_pages_gtt => i915_gem_object_get_pages => i915_gem_object_pin => i915_gem_execbuffer_reserve_object.isra.11 => i915_gem_execbuffer_reserve => i915_gem_do_execbuffer.isra.15 => i915_gem_execbuffer2 => drm_ioctl => do_vfs_ioctl => SyS_ioctl => system_call_fastpath Xorg-1194 [003] .... 1796.441672: => __kmalloc => i915_gem_execbuffer2 => drm_ioctl => do_vfs_ioctl => SyS_ioctl => system_call_fastpath So the trace output shows exactly 5 stacktraces, as expected. Just for comparison, let's look at an event that's harder to trigger, to see a count that isn't 0 in the trigger description: # echo 'stacktrace:5 if bytes_req >= 65536' > \ /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger stacktrace:count=5 if bytes_req >= 65536 The next example shows how to use the 'snapshot' command to capture a snapshot of the trace buffer when an 'interesting' event occurs. In this case, we'll first start the entire block subsystem tracing: # echo 1 > /sys/kernel/debug/tracing/events/block/enable Next, we add a 'snapshot' trigger that will take a snapshot of all the events leading up to the particular event we're interested in, which is a block queue unplug with a depth > 1. In this case we're interested in capturing the snapshot just one time, the first time it occurs: # echo 'snapshot:1 if nr_rq > 1' > \ /sys/kernel/debug/tracing/events/block/block_unplug/trigger It may take awhile for the condition to occur, but once it does, we can see the entire sequence of block events leading up to in in the 'snapshot' file: # cat /sys/kernel/debug/tracing/snapshot jbd2/sdb1-8-278 [001] .... 382.075012: block_bio_queue: 8,16 WS 629429976 + 8 [jbd2/sdb1-8] jbd2/sdb1-8-278 [001] .... 382.075012: block_bio_backmerge: 8,16 WS 629429976 + 8 [jbd2/sdb1-8] jbd2/sdb1-8-278 [001] d... 382.075015: block_rq_insert: 8,16 WS 0 () 629429912 + 72 [jbd2/sdb1-8] jbd2/sdb1-8-278 [001] d... 382.075030: block_rq_issue: 8,16 WS 0 () 629429912 + 72 [jbd2/sdb1-8] jbd2/sdb1-8-278 [001] d... 382.075044: block_unplug: [jbd2/sdb1-8] 1 -0 [000] ..s. 382.075310: block_rq_complete: 8,16 WS () 629429912 + 72 [0] jbd2/sdb1-8-278 [000] .... 382.075407: block_touch_buffer: 8,17 sector=78678492 size=4096 jbd2/sdb1-8-278 [000] .... 382.075413: block_bio_remap: 8,16 FWFS 629429984 + 8 <- (8,17) 629427936 jbd2/sdb1-8-278 [000] .... 382.075415: block_bio_queue: 8,16 FWFS 629429984 + 8 [jbd2/sdb1-8] jbd2/sdb1-8-278 [000] .... 382.075418: block_getrq: 8,16 FWFS 629429984 + 8 [jbd2/sdb1-8] jbd2/sdb1-8-278 [000] d... 382.075421: block_rq_insert: 8,16 FWFS 0 () 629429984 + 8 [jbd2/sdb1-8] jbd2/sdb1-8-278 [000] d... 382.075424: block_rq_issue: 8,16 FWS 0 () 18446744073709551615 + 0 [jbd2/sdb1-8] -0 [000] dNs. 382.115912: block_rq_issue: 8,16 WS 0 () 629429984 + 8 [swapper/0] -0 [000] ..s. 382.116059: block_rq_complete: 8,16 WS () 629429984 + 8 [0] -0 [000] dNs. 382.116079: block_rq_issue: 8,16 FWS 0 () 18446744073709551615 + 0 [swapper/0] -0 [000] d.s. 382.131030: block_rq_complete: 8,16 WS () 629429984 + 0 [0] jbd2/sdb1-8-278 [000] .... 382.131106: block_dirty_buffer: 8,17 sector=26 size=4096 jbd2/sdb1-8-278 [000] .... 382.131111: block_dirty_buffer: 8,17 sector=106954757 size=4096 . . . kworker/u16:3-66 [002] .... 387.144505: block_bio_remap: 8,16 WM 2208 + 8 <- (8,17) 160 kworker/u16:3-66 [002] .... 387.144512: block_bio_queue: 8,16 WM 2208 + 8 [kworker/u16:3] kworker/u16:3-66 [002] .... 387.144522: block_getrq: 8,16 WM 2208 + 8 [kworker/u16:3] kworker/u16:3-66 [002] .... 387.144525: block_plug: [kworker/u16:3] kworker/u16:3-66 [002] .... 387.144530: block_bio_remap: 8,16 WM 2216 + 8 <- (8,17) 168 kworker/u16:3-66 [002] .... 387.144531: block_bio_queue: 8,16 WM 2216 + 8 [kworker/u16:3] kworker/u16:3-66 [002] .... 387.144533: block_bio_backmerge: 8,16 WM 2216 + 8 [kworker/u16:3] . . . kworker/u16:3-66 [002] d... 387.144631: block_rq_insert: 8,16 WM 0 () 2208 + 16 [kworker/u16:3] kworker/u16:3-66 [002] d... 387.144636: block_rq_insert: 8,16 WM 0 () 2256 + 16 [kworker/u16:3] kworker/u16:3-66 [002] d... 387.144638: block_rq_insert: 8,16 WM 0 () 662702080 + 8 [kworker/u16:3] kworker/u16:3-66 [002] d... 387.144640: block_rq_insert: 8,16 WM 0 () 683673680 + 8 [kworker/u16:3] kworker/u16:3-66 [002] d... 387.144641: block_rq_insert: 8,16 WM 0 () 729812344 + 8 [kworker/u16:3] kworker/u16:3-66 [002] d... 387.144642: block_rq_insert: 8,16 WM 0 () 729828896 + 8 [kworker/u16:3] kworker/u16:3-66 [002] d... 387.144643: block_rq_insert: 8,16 WM 0 () 730599480 + 8 [kworker/u16:3] kworker/u16:3-66 [002] d... 387.144644: block_rq_insert: 8,16 WM 0 () 855640104 + 8 [kworker/u16:3] kworker/u16:3-66 [002] d... 387.144645: block_rq_insert: 8,16 WM 0 () 880805984 + 8 [kworker/u16:3] kworker/u16:3-66 [002] d... 387.144646: block_rq_insert: 8,16 WM 0 () 1186990400 + 8 [kworker/u16:3] kworker/u16:3-66 [002] d... 387.144649: block_unplug: [kworker/u16:3] 10 The final example shows something very similer but using the 'traceoff' command to stop tracing when an 'interesting' event occurs. The traceon and traceoff commands can be used together to toggle tracing on and off in creative ways to capture different traces in the 'trace' buffer, but this example just shows essentially the same use case as the previous example but using 'traceoff' to capture trace data of interest in the standard 'trace' buffer. Again, we'll start the entire block subsystem tracing: # echo 1 > /sys/kernel/debug/tracing/events/block/enable # echo 'traceoff:1 if nr_rq > 1' > \ /sys/kernel/debug/tracing/events/block/block_unplug/trigger # cat /sys/kernel/debug/tracing/trace kworker/u16:4-67 [000] .... 803.003670: block_bio_remap: 8,16 WM 2208 + 8 <- (8,17) 160 kworker/u16:4-67 [000] .... 803.003670: block_bio_queue: 8,16 WM 2208 + 8 [kworker/u16:4] kworker/u16:4-67 [000] .... 803.003672: block_getrq: 8,16 WM 2208 + 8 [kworker/u16:4] kworker/u16:4-67 [000] .... 803.003674: block_bio_remap: 8,16 WM 2216 + 8 <- (8,17) 168 kworker/u16:4-67 [000] .... 803.003675: block_bio_queue: 8,16 WM 2216 + 8 [kworker/u16:4] kworker/u16:4-67 [000] .... 803.003676: block_bio_backmerge: 8,16 WM 2216 + 8 [kworker/u16:4] kworker/u16:4-67 [000] .... 803.003678: block_bio_remap: 8,16 WM 2232 + 8 <- (8,17) 184 kworker/u16:4-67 [000] .... 803.003678: block_bio_queue: 8,16 WM 2232 + 8 [kworker/u16:4] kworker/u16:4-67 [000] .... 803.003680: block_getrq: 8,16 WM 2232 + 8 [kworker/u16:4] . . . kworker/u16:4-67 [000] d... 803.003720: block_rq_insert: 8,16 WM 0 () 285223776 + 16 [kworker/u16:4] kworker/u16:4-67 [000] d... 803.003721: block_rq_insert: 8,16 WM 0 () 662702080 + 8 [kworker/u16:4] kworker/u16:4-67 [000] d... 803.003722: block_rq_insert: 8,16 WM 0 () 683673680 + 8 [kworker/u16:4] kworker/u16:4-67 [000] d... 803.003723: block_rq_insert: 8,16 WM 0 () 730599480 + 8 [kworker/u16:4] kworker/u16:4-67 [000] d... 803.003724: block_rq_insert: 8,16 WM 0 () 763365384 + 8 [kworker/u16:4] kworker/u16:4-67 [000] d... 803.003725: block_rq_insert: 8,16 WM 0 () 880805984 + 8 [kworker/u16:4] kworker/u16:4-67 [000] d... 803.003726: block_rq_insert: 8,16 WM 0 () 1186990872 + 8 [kworker/u16:4] kworker/u16:4-67 [000] d... 803.003727: block_rq_insert: 8,16 WM 0 () 1187057608 + 8 [kworker/u16:4] kworker/u16:4-67 [000] d... 803.003729: block_unplug: [kworker/u16:4] 14 The following changes since commit fc30f13b7c1b87b44ee364462c3408c913f01439: Merge branch 'trace/ftrace/core-tpstring' into trace/for-next (2013-08-22 12:30:55 -0400) are available in the git repository at: git://git.yoctoproject.org/linux-yocto-contrib.git tzanussi/event-triggers-v8 http://git.yoctoproject.org/cgit/cgit.cgi/linux-yocto-contrib/log/?h=tzanussi/event-triggers-v8 Tom Zanussi (10): tracing: Add support for SOFT_DISABLE to syscall events tracing: Add basic event trigger framework tracing: Add 'traceon' and 'traceoff' event trigger commands tracing: Add 'snapshot' event trigger command tracing: Add 'stacktrace' event trigger command tracing: Add 'enable_event' and 'disable_event' event trigger commands tracing: Add and use generic set_trigger_filter() implementation tracing: Update event filters for multibuffer tracing: Add documentation for trace event triggers tracing: Make register/unregister_ftrace_command __init Documentation/trace/events.txt | 207 +++++ include/linux/ftrace.h | 4 +- include/linux/ftrace_event.h | 52 +- include/trace/ftrace.h | 47 +- kernel/trace/Makefile | 1 + kernel/trace/ftrace.c | 12 +- kernel/trace/trace.c | 53 +- kernel/trace/trace.h | 214 +++++- kernel/trace/trace_branch.c | 2 +- kernel/trace/trace_events.c | 46 +- kernel/trace/trace_events_filter.c | 231 +++++- kernel/trace/trace_events_trigger.c | 1371 ++++++++++++++++++++++++++++++++++ kernel/trace/trace_export.c | 2 +- kernel/trace/trace_functions_graph.c | 4 +- kernel/trace/trace_kprobe.c | 4 +- kernel/trace/trace_mmiotrace.c | 4 +- kernel/trace/trace_sched_switch.c | 4 +- kernel/trace/trace_syscalls.c | 73 +- kernel/trace/trace_uprobe.c | 3 +- 19 files changed, 2206 insertions(+), 128 deletions(-) create mode 100644 kernel/trace/trace_events_trigger.c -- 1.7.11.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/